The present invention relates to an apparatus for the precision measurement of the optical characteristics of the eye and the shape of the cornea and, more particularly, to an optical characteristic measuring apparatus capable of measuring the optical characteristics of an irregular astigmatism component.
A conventional optical characteristic measuring apparatus for measuring the optical characteristics of the eye known as a refractometer is capable of expressing the optical characteristics of the eye merely as a spherical component, a regular astigmatism component and the angle of the axis of the regular astigmatism component.
Some eyes have an irregular astigmatism component in addition to a regular astigmatism component. Irregular astigmatism cannot be corrected by a pair of spectacles if the quantity of the irregular astigmatism component is large, contact lens must be used instead of a pair of spectacles lens, and the eye must be examined by a medical doctor.
However, the conventional optical characteristic measuring apparatus for measuring the optical characteristics of the eye, such as a refractometer, is used only for reforming a pair of spectacles and its performance is not fully satisfactory. Accordingly, desired eagerly was an of an optical characteristic measuring apparatus capable of accurately measuring the irregular astigmatism component of the eye in addition to the spherical component, the regular astigmatism component and the angle of the axis of the regular astigmatism component
An optical characteristic measuring apparatus according to one aspect of the present invention comprises an illuminating optical system for illuminating a minute region on the retina of the eye with light emitted by an illuminating light source; a light receiving optical system for receiving light reflected from the retina of the eye and for guiding the reflected light to a light receiving device; a converting device for converting the reflected light into at least seventeen light beams and sending the light beams to the light receiving device; and an arithmetic unit for determining the optical characteristics of the eye and the shape of the cornea of the eye on the basis of the inclination of light rays fallen on the light receiving device.